Nikki Reed and Ian Somerhalder argue about the colour of his eyes.

Nikki Reed and Ian Somerhalder

Nikki Reed and Ian Somerhalder

Ian - who proposed to the 'Twilight' actress in January after six months of dating - believes he has aqua-coloured eyes whilst his fiancée is convinced her husband-to-be's eyes are ocean blue.

When asked if they argued about anything, she said: "He thinks his eyes are ocean blue and I think they're aqua."

The 26-year-old actress couldn't help but gush about her beautiful engagement ring, which has diamonds in the shape of a flower.

She said: "Can't tell you anything about it other than I love it more than anything in the world!"

Meanwhile, Nikki believes her bond with 'The Vampire Diaries' star stems from their similar beliefs and passions.

She told US Weekly magazine: "Most of our conversations revolve around (what we can do better), because whether or not we have similar passions, I think it all stems around the idea that everything is connected.

"What's nurtured this long friendship that we've had is that we are passionate about similar things, whether it's animals or the environment or education or climate change. So we do wake up in the morning and talk about those things."